The present invention relates to a radial arm saw guard with operational interlock and an adjustable outfeed user barrier, and more particularly, to an operational interlock that prevents rip cutting by a motor driven saw blade unless an adjustable outfeed user barrier is in a lower engaged position, as well as to an adjustable outfeed user barrier which is adjustable to workpieces of different thickness and for accommodating motor driven saw blades of different diameter.
Typically, a radial saw is mounted on a supporting arm that overhangs a worktable. The supporting arm is mounted at an upper end of a base or column that extends upwardly from one end of a worktable. A motor driven saw blade is pivotally and slidably mounted to the supporting arm for operating the motor driven saw blade in rip cutting workpieces longitudinally along the length of a rip fence or for cross cutting of workpieces transverse to the rip fence.
Because the radial saw is operated in fixed and moving relationship in two different directions for rip cutting and cross cutting, different safety hazards can arise from improper use of the radial saw. In order to fully appreciate the nature of the safety hazards involved in rip cutting and cross cutting, it is important to understand the nature of the rip cutting and cross cutting operations. Rip cutting involves the changing of the width of a workpiece by cutting along its length. The workpiece is fed into the motor driven saw blade, which rotates in a fixed position, parallel to a rip fence, and at a set distance from the rip fence, enabling the fence to serve as a guide for the workpiece to be cut. Cross cutting, on the other hand, is cutting a workpiece to length. The workpiece is held firmly against the workpiece fence, and the blade is pulled through the workpiece to make the cut. Straight, bevel, miter and compound cuts can be made.
The safety hazards associated with rip cutting include outfeed zone hazard, kickback and wrong way feeding. If the operator reaches around the blade to the outfeed side and tries to hold or pull the workpiece through, the rotational force of the blade can pull the hand back into the blade. Therefore, touching, holding or pulling on the outfeed of a workpiece, while the blade is still spinning, can result in fingers, hand or an arm being cut off. Kickback occurs when a blade is pinched or bound by a workpiece. This can result in the work being thrown out of the radial saw in the direction of a user causing personal injury. Wrong way feed is an attempt to feed the workpiece into the outfeed side of the blade. Rotational force can pull the workpiece into the blade if the workpiece is fed in the same direction as the blade rotates. As a result, hands and fingers could be pulled along with the workpiece into the spinning blade before the user can let go or pull back. Not only can fingers, hand or an arm be cut off, but a propelled workpiece could injure a bystander.
Cross cutting safety hazards include exposed blade teeth, rolling carriage and thrown workpiece. During cross cutting, blade teeth can be exposed which if contacted can result in potential damage to the fingers, hand or arm of a user. Rolling carriage hazard occurs when the spinning blade inadvertently touches a workpiece or is lowered into the table causing the blade to suddenly come forward. This creates a risk to the user whose hands may be in the path of the blade. Finally, thrown workpiece hazard occurs when a workpiece is picked up by a spinning blade and thrown. A user or bystander could be hit by the thrown workpiece.
As will be understood from the discussion that follows, the present invention employs numerous safety and operational features in a radial saw which overcome many of the rip cutting and cross cutting hazards to which a user can be exposed through improper operation of the saw. As a result, the difference of the present invention from the prior art designs will be readily apparent to those skilled in the art.
In prior copending U.S. Pat. application Ser. No. 08,031,344 filed Mar. 15, 1993 entitled "RADIAL SAW SAFETY GUARDS AND BARRIERS", numerous safety and operational features in a radial saw have been disclosed. The present invention discloses some of the same features as in the aforementioned copending application, but also includes an operational interlock to prevent operation of the saw for rip cutting unless an adjustable outfeed user barrier is in a lower engaged position. The present invention also discloses an adjustable outfeed user barrier which is adjustable not only for workpieces of different thickness, but is also adjustable for motor driven saw blades of different diameter. Other safety features are employed in connection with the operational interlock and adjustable outfeed user barrier in order to overcome many of the rip cutting and cross cutting hazards to which a user and bystander may be exposed.